Endocrine Abstracts

Objective: Acromegaly is often accompanied by abnormalities in glucose and lipid metabolism, which tend to ameliorate upon treatment. However, few studies have investigated whether glucose homeostasis and lipid profiles are differently affected by different treatment regimens. This study aimed to compare glucose homeostasis and lipid profiles in patients with acromegaly who are well-controlled after surgery or under stable treatment with long-acting somatostatin analogs (SSA) either in monotherapy or in combination with pegvisomant.

Methods: Cross-sectional study in 21 patients with a diagnosis of acromegaly (aged 59.1±10.9 years, 10 males), who were controlled (i.e. serum IGF-1 levels under sex- and age-specific thresholds) after surgery (SUR; n=5) or under treatment with SSA (SSA; n=10) or SSA + pegvisomant (COMBI; n=6). Glucose, insulin, total cholesterol, HDL-C and LDL-C were measured from fasting serum samples. Triglycerides were measured during a mixed-meal tolerance test (MMTT). Insulin resistance was evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR); insulin sensitivity was evaluated by hyperinsulinemic-euglycemic clamp.

Results: IGF-1 levels tended to be lower in SUR (138.4±54.4 ng/ml) as compared to SSA (194.5±16.3 ng/ml) or COMBI (173.3±52.3 ng/ml) (P=0.056). After adjustment for age and BMI, between-group differences were observed for HbA1c (P=0.048), fasting glucose (P=0.022), and HDL-C (P=0.015), with lower levels in SUR as compared to SSA or COMBI. No differences were observed in fasting insulin, cholesterol, LDL-C, HOMA-IR, glucose disposal rate during clamp, or triglyceride levels during MMTT. Independently of the treatment regimen, IGF-1 levels correlated positively with fasting glucose and insulin levels (ß=0.52 and ß=0.57, both P=0.010), with HOMA-IR (ß=0.66, P=0.003), and inversely with glucose disposal rate (ß=−0.60, P=0.006).

Conclusion: In patients with acromegaly who are controlled after surgery or under stable medical therapy, indices of glucose homeostasis correlate with circulating IGF-1 levels, independently of the treatment regimen.